"Customers have strict requirements for the weight of the ball. A small deviation can have a big influence on its trajectory and speed," said Wu Jili, a quality inspector at the company.

Geography makes Dushan an important link between inland Guizhou and major coastal ports in Guangdong province and Guangxi Zhuang autonomous region. Products can be transported to ports in one day.

The company started in 2003, taking advantage of the local government's favorable tax policies for outside investment.